Danger originally preventing return of old Italian currency (5)
I believe the answer is:
peril
'danger' is the definition.
(peril is a kind of danger)
'originally preventing return of old italian currency' is the wordplay.
'originally' suggests taking the first letters.
'return of' says the letters should be written in reverse.
'old italian currency' becomes 'lire' (I've seen this in another clue).
The initial letter of 'preventing' is 'p'.
'lire' backwards is 'eril'.
'p'+'eril'='PERIL'
(Other definitions for peril that I've seen before include "Source of danger" , "Immediate danger" , "Danger of serious kind" , "Danger, jeopardy" , "Exposure to harm" .)